Flexible interconnect circuits and methods of fabrication thereof

ABSTRACT

Provided are flexible interconnect circuit assemblies and methods of fabricating thereof. In some examples, a flexible interconnect circuit comprises multiple circuit portions, which are monolithically integrated. During the fabrication, some of these circuit portions are folded relative to other portions, forming a stack in each fold. For example, the initial orientation of these portions can be selected such that smaller sheets can be used for circuit fabrication. The portions are then unfolded into the final design configuration. In some examples, the assembly also comprises a bonding film and a temporary support film attached to the bonding film such that the two circuit portions at least partially overlap with the bonding film and are positioned between the bonding film and temporary support film. In some examples, at least some circuit portions extend past the boundary of the bonding film and are coupled to connectors.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(e) of (1) USProvisional Patent Application 63/268,358 (Attorney Docket No.CLNKP020P) by Jean-Paul Ortiz, et al., entitled: “Folded Arrangements ofFlexible interconnect Circuits and Methods of Fabricated Thereof”, filedon 2022 Feb. 22, (2) U.S. Provisional Patent Application 63/363,032(Attorney Docket No. CLNKP021P) by Jean-Paul Ortiz, et al., entitled:“Flexible Interconnect Circuits with Integrated Circuit Elements”, filedon 2022-Apr. 2015, and (3) U.S. Provisional Patent Application63/373,829 by Mark Terlaak, et al., entitled: “Molded Seal InterconnectHarness”, filed on 2022 Aug. 29, all of which are incorporated herein byreference in its entirety for all purposes.

BACKGROUND

Electrical power and control signals are typically transmitted toindividual components (e.g., in a vehicle or any other machinery orsystem) using multiple wires bundled together in a harness. While flatflexible interconnect circuits are gaining traction for suchapplications, forming such circuits requires large sheets of metal foiland insulators most of these materials are being wasted. Furthermore,transporting and installing flexible interconnect circuits can bechallenging due to their large flat arrangements.

What is needed are novel flexible interconnect circuits that are foldedinto specific configurations thereby reducing the material waste duringfabrication and/or also improving the installation efficiency.

SUMMARY

Provided are flexible interconnect circuit assemblies and methods offabricating thereof. In some examples, a flexible interconnect circuitcomprises multiple circuit portions, which are monolithicallyintegrated. During the fabrication, some of these circuit portions arefolded relative to other portions, forming a stack in each fold. Forexample, the initial orientation of these portions can be selected suchthat smaller sheets can be used for circuit fabrication. The portionsare then unfolded into the final design configuration. In some examples,the assembly also comprises a bonding film and a temporary support filmattached to the bonding film such that the two circuit portions at leastpartially overlap with the bonding film and are positioned between thebonding film and the temporary support film. In some examples, at leastsome circuit portions extend past the boundary of the bonding film andare coupled to connectors.

Provided is a method of forming a flexible interconnect circuitassembly. In some examples, the method comprises providing a flexibleinterconnect circuit comprising a first circuit portion and a secondcircuit portion monolithically integrated with the first circuitportion. Each of the first circuit portion and the second circuitportion is an elongated structure extending parallel to a primary axisof the flexible interconnect circuit. Each of the first circuit portionand the second circuit portion comprises a first side and a second sideopposite the first side. The first side of the first circuit portion andthe first side of the second circuit portion face in the same direction.The method also comprises folding the second circuit portion relative tothe first circuit portion such that the second circuit portion is nolonger parallel to the primary axis of the flexible interconnect circuitand such that the second side of the first circuit portion and thesecond side of the second circuit portion face in opposite directionsafter folding. The method also comprises attaching a bonding film to thesecond side of the first circuit portion and the first side of thesecond circuit portion and attaching a temporary support film to thebonding film such that the first side of the first circuit portion andthe second side of the second circuit portion faces the temporarysupport film.

In some examples, the first circuit portion terminates with a firstconnector. The first connector and a part of the first circuit portion,which is adjacent to the first connector, extend outside the boundary ofthe bonding film. In some examples, the first connector and the portionof the first circuit portion adjacent to the first connector overlapwith the boundary of the temporary support film.

In some examples, before folding, the first circuit portion and thesecond circuit portion are coplanar. In the same or other examples,after folding, a part of the first side of the first circuit portiondirectly interfaces with a part of the first side of the second circuitportion.

In some examples, the first side of the first circuit portion and thefirst side of the second circuit portion is formed by a first insulatinglayer, which is monolithic. The second side of the first circuit portionand the second side of the second circuit portion is formed by a secondinsulating layer, which is monolithic and bonded to the first insulatinglayer. In more specific examples, each of the first circuit portion andsecond circuit portion comprises one or more conductive traces,positioned between the first insulating layer and the second insulatinglayer such that the first insulating layer and the second insulatinglayer are bonded together around the one or more conductive traces. Insome examples, providing the flexible interconnect circuit comprisesforming one or more conductive traces of the first circuit portion andsecond circuit portion by patterning a metal foil.

In some examples, the first circuit portion and a second circuit portionform a primary circuit portion. The flexible interconnect circuitcomprises support tabs, each formed by at least the first insulatorlayer and the second insulator layer and extending from an edge of theprimary circuit portion and monolithic with the primary circuit portion.Each of the support tabs comprises a support-tab opening for receiving afastener when securing the flexible interconnect circuit.

In more specific examples, the flexible interconnect circuit comprisesconductive traces and a support component, which are formed from thesame conductive materials and have the same thicknesses. The conductivetraces are at least partially positioned between the first insulatorlayer and the second insulator layer in the primary circuit portion. Thesupport component is at least partially positioned between the firstinsulator layer and the second insulator layer in the support tab and isused to reinforce the support tab providing additional strength. In someexamples, the support component is electrically isolated from each ofthe conductive traces. Alternatively, the support component ismonolithic with at least one of the conductive traces. In some examples,the second insulator layer comprises a second-insulator opening that islarger and concentric with the support-tab opening. The second insulatorlayer at least partially exposes the support component.

In some examples, the first circuit portion and the second circuitportion, extending parallel to each other, are separated by a slit. Inthe same or other examples, the method further comprises arranging theflexible interconnect circuit into a shipping configuration selectedfrom the group consisting of a planar sheet and a roll, wherein the rollcomprises additional flexible interconnect circuits.

In some examples, a flexible interconnect circuit assembly comprises aflexible interconnect circuit comprising a first circuit portion and asecond circuit portion monolithically integrated with the first circuitportion. Each of the first circuit portion and the second circuitportion comprises a first side and a second side opposite the firstside. The first side of the first circuit portion and the first side ofthe second circuit portion is formed by a first insulating layer. Thesecond side of the first circuit portion and the second side of thesecond circuit portion is formed by a second insulating layer, bonder tothe first insulating layer. The second circuit portion is foldedrelative to the first circuit portion such that the second circuitportion is not parallel to the second circuit portion and such that thefirst side of the first circuit portion and the first side of the secondcircuit portion face in opposite directions. The flexible interconnectcircuit assembly also comprises a bonding film attached to the secondside of the first circuit portion and the first side of the secondcircuit portion and a temporary support film attached to the bondingfilm such that the first side of the first circuit portion and thesecond side of the second circuit portion faces the temporary supportfilm.

In some examples, the flexible interconnect circuit assembly furthercomprises the first circuit portion, which terminates with a firstconnector. The first connector and a part of the first circuit portionadjacent to the first connector extend outside the boundary of thebonding film. The first connector and the portion of the first circuitportion adjacent to the first connector overlap with the boundary of thetemporary support film. In some examples, the first side of the firstcircuit portion and the first side of the second circuit portion isformed by a first insulating layer, which is monolithic. The second sideof the first circuit portion and the second side of the second circuitportion is formed by a second insulating layer, which is monolithic andbonded to the first insulating layer. In more specific examples, each ofthe first circuit portion and second circuit portion comprises one ormore conductive traces, positioned between the first insulating layerand the second insulating layer such that the first insulating layer andthe second insulating layer are bonded together around the one or moreconductive traces.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic planar view of a flexible interconnect circuit ina pre-folded state with a first side facing up, in accordance with someexamples.

FIG. 1B is a schematic planar view of the flexible interconnect circuitin FIG. 1A, also in a pre-folded state with the first side facing down.

FIG. 1C is a schematic cross-sectional view of the flexible interconnectcircuit in FIG. 1A, also in a pre-folded state with the first sidefacing down.

FIG. 1D is a schematic planar view of the flexible interconnect circuitin FIG. 1A in an unfolded state.

FIG. 1E is a schematic cross-sectional view of a portion of the flexibleinterconnect circuit in FIG. 1D.

FIGS. 2A and 2B are schematic planar views of the flexible interconnectcircuit in FIG. 1D in an unfolded state with a bonding film, inaccordance with some examples.

FIG. 3A is a schematic planar view of the flexible interconnect circuitin FIG. 1D in an unfolded state with a bonding film and a temporarysupport film, in accordance with some examples.

FIGS. 3B, 3C, and 3D are schematic cross-sectional views of differentparts of the flexible interconnect circuit in FIG. 3A.

FIG. 4A is a schematic planar view of a flexible interconnect circuitassembly comprising multiple flexible interconnect circuits positionedon the same temporary support film, in accordance with some examples.

FIG. 4B is a schematic side of the flexible interconnect circuitassembly in FIG. 4A that is arranged into a roll, in accordance withsome examples.

FIG. 5 is a process flowchart corresponding to a method of fabricating aflexible interconnect circuit assembly, in accordance with someexamples.

FIG. 6 is a process flowchart corresponding to a method of installing aflexible interconnect circuit assembly on a base structure, inaccordance with some examples.

FIGS. 7A, 7B, and 7C are schematic views of a flexible interconnectcircuit during the installation of this assembly on a base structure, inaccordance with some examples.

FIG. 8A is a schematic planar view of a flexible interconnect circuit,comprising a flap portion, in a pre-folded state, in accordance withsome examples.

FIG. 8B is a schematic cross-sectional view of the flexible interconnectcircuit in FIG. 8A, in a pre-folded state.

FIG. 8C is a schematic cross-sectional view of the flexible interconnectcircuit in FIG. 8A, in a folded state.

FIG. 9A is a schematic planar view of a flexible interconnect circuit,comprising a segmented flap portion, in a pre-folded state, inaccordance with some examples.

FIGS. 9B and 9C are schematic cross-sectional views of the flexibleinterconnect circuit in FIG. 9A at different locations.

FIG. 10A is a schematic planar view of a flexible interconnect circuit,comprising flap portions on different sides of the circuit, in apre-folded state, in accordance with some examples.

FIGS. 1013 and 10C are schematic cross-sectional views of one portion ofthe flexible interconnect circuit in FIG. 10A in pre-folder and foldedstates.

FIGS. 10D and 10E are schematic cross-sectional views of another portionof the flexible interconnect circuit in FIG. 10A in pre-folder andfolded states.

FIG. 10F is a schematic cross-sectional view of the portion of theflexible interconnect circuit shown in FIG. 10F after flipping thatportion.

FIG. 11 is a schematic planar view of the flexible interconnect circuitin FIG. 10A in an unfolded state, in accordance with some examples.

FIG. 12 is a process flowchart corresponding to a method of fabricatinga flexible interconnect circuit assembly, in accordance with someexamples

FIG. 13A is a cross-sectional side view of a flexible interconnectcircuit comprising a connector-support portion with a reinforcementmetal layer, in accordance with some examples.

FIG. 13B is a top view of the flexible interconnect circuit in FIG. 13Athat shows \conductive leads (of an exposed portion) and notches forengaging a connector, in accordance with some examples.

FIG. 13C is a cross-sectional side view of another example of a flexibleinterconnect circuit comprising a connector-support portion with anexposed reinforcement metal layer, in accordance with some examples.

FIG. 14A is a cross-sectional side view of a flexible interconnectassembly, utilizing the flexible interconnect circuit in FIG. 13A, thatcomprises a connector.

FIG. 14B is a top cross-sectional view of the flexible interconnectassembly in FIG. 14A, showing the retention pins of the connectorextending into the notches of the flexible interconnect circuit, inaccordance with some examples.

FIG. 15A is a schematic top view of a flexible interconnect circuitcomprising support tabs for attaching this flexible interconnect circuitto a support structure, in accordance with some examples.

FIG. 15B is a schematic top cross-sectional view of a portion of theflexible interconnect circuit in FIG. 15A, illustrating variouscomponents of the support tab, in accordance with some examples.

FIGS. 15C and 15D are schematic side cross-sectional views of a supporttab, used in a flexible interconnect circuit, positioned over andattached to a support structure with a fastener, in accordance with someexamples.

FIG. 16A is a top schematic view of a flexible interconnect circuitcomprising contact traces with temporary support links, in accordancewith some examples.

FIG. 16B is a side schematic view of the flexible interconnect circuitin FIG. 16B, which illustrates one example of the temporary supportlinks, in accordance with some examples.

FIGS. 16C and 16D are top schematic views of a portion of the flexibleinterconnect circuit illustrating additional examples of the temporarysupport links, in accordance with some examples.

FIGS. 16E, 16F, and 16G are schematic side cross-sectional views ofdifferent stages while attaching a connector to the flexibleinterconnect circuit of FIGS. 16A-16B, in accordance with some examples.

FIG. 17A is a schematic side cross-sectional view of a flexibleinterconnect circuit illustrating the two conductive layers being laserwelded through the insulating layer positioned on the laser beam path,in accordance with some examples.

FIG. 17B is a schematic top view of a flexible interconnect circuitillustrating a weld nugget formed in the two conductive layers, inaccordance with some examples.

FIG. 17C is a process flowchart corresponding to a method for laserwelding the two conductive layers of a flexible interconnect circuitthrough the insulating layer positioned on the laser beam path, inaccordance with some examples.

FIG. 18A is a schematic planar view of a molded seal flexibleinterconnect circuit in a pre-folded state with a first side facing up,in accordance with some examples, in accordance with some examples.

FIG. 18B is a schematic cross-sectional view of the molded seal flexibleinterconnect circuit in FIG. 18A in accordance with some examples.

FIGS. 19A, 19B, 19C, 19D, and 19E, illustrate views of a molded sealflexible interconnect circuit positioned within certain assemblies, inaccordance with some examples.

FIGS. 20A and 20B illustrate cross-sectional views of another examplemolded seal flexible interconnect circuit positioned within certainassemblies, in accordance with some examples.

FIGS. 21A and 21B illustrate schematic planar views illustrating atechnique of forming a molded seal flexible interconnect circuit, inaccordance with some examples.

FIGS. 21C and 21D illustrate schematic planar views illustrating anothertechnique of forming a molded seal flexible interconnect circuit, inaccordance with some examples.

FIGS. 21E, 21F, and 21G illustrate schematic planar views illustrating afurther technique of forming a molded seal flexible interconnectcircuit, in accordance with some examples.

FIG. 22 illustrates a process flow chart corresponding to an examplemethod for forming a molded seal flexible interconnect circuit, inaccordance with one or more examples.

FIGS. 23A, 23B, and 23C illustrate schematic planar views illustratingmolded seal flexible interconnect circuits in various assemblies, inaccordance with some examples.

DETAILED DESCRIPTION

In the following description, numerous specific details are outlined toprovide a thorough understanding of the presented concepts. In someexamples, the presented concepts are practiced without some or all ofthese specific details. In other examples, well-known process operationshave not been described in detail to unnecessarily obscure the describedconcepts. While some concepts will be described in conjunction withspecific examples, it will be understood that these examples are notintended to be limiting.

Flexible interconnect circuits are used to deliver power and/or signalsand are used for various applications, such as vehicles, appliances,electronics, and the like. One example of such flexible interconnectcircuits is a harness. As noted above, a conventional harness uses astranded set of small round wires. A separate polymer shell insulateseach wire, adding to the size and weight of the harness. Unlikeconventional harnesses, flexible interconnect circuits described hereinhave thin flat profiles, enabled by thin electrical conductors that canbe positioned side-by-side. Each electrical conductor can have a flatrectangular profile. In some examples, electrical conductors (positionednext to each other) are formed from the same metal sheet (e.g., foil).For purposes of this disclosure, the term “interconnect” is usedinterchangeably with “interconnect circuit”, the term “conductivelayer”—with “conductor” or “conductor layer”, and the term “insulatinglayer”—with “insulator”.

FIGS. 1A-4B: Examples of Flexible Interconnect Circuit Assemblies

As noted above, fabricating flat flexible interconnect circuits solvedmany problems associated with conventional wire harnesses but causessignificant material waste. For example, the overall boundary of aninterconnect circuit can be much larger than the area occupied by theactual physical portions of the circuit (e.g., conductive traces). Thislimitation is caused by conventional methods of manufacturinginterconnect circuits, i.e., starting with sheets of materials thatextend the entire circuit boundary and removing (e.g., scrapping) theunused portions.

Flexible interconnect circuit assemblies, described herein, arefabricated by folding different circuit portions relative to each other.For example, two circuit portions can be initially parallel and next toeach other. One circuit portion can be folded such that it extends in adifferent direction, e.g., perpendicular, to the other portion therebyincreasing the overall footprint area of interconnect circuit assembly.It should be noted that both circuit portions are formed from the samestarting sheets of materials and, therefore, are monolithicallyintegrated. To assist with bonding the circuit assembly to varioussurfaces (e.g., vehicle panels), the assembly can comprise a bondingfilm and a temporary support film attached to the bonding film such thatthe circuit portions at least partially overlap with the bonding filmand positioned between the bonding film and temporary support film. Insome examples, a part of the first circuit portion extends past theboundary of the bonding film and is coupled to a connector. In otherwords, an interconnect circuit assembly comprises a flexibleinterconnect circuit, which is initially fabricated in a pre-foldedstate thereby reducing the size of materials (e.g., sheets) needed formanufacturing the circuit. The flexible interconnect circuit is thenunfolded such that the unfolded state corresponds to the applicationfootprint (greater than the initial fabricating footprint of theflexible interconnect circuit). Additional assembly components are addedto the flexible interconnect circuit in the unfolded state forming theassembly.

FIG. 1A is a schematic view of flexible interconnect circuit 100 in apre-folded state with first side 103 facing up, in accordance with someexamples. FIG. 1B is a schematic view of flexible interconnect circuit100 in FIG. 1B with second side 104 (opposite of first side 103) facingup. FIGS. 1A and 1B as well as other figures also identify first edge101 and second edge 102 to provide the orientation of flexibleinterconnect circuit 100 and its component in space. The pre-foldedstate may be also referred to as an as-manufactured state. Thisstate/shape is selected to reduce the material waste during themanufacturing of flexible interconnect circuit 100. FIG. 1D is aschematic view of flexible interconnect circuit 100 in FIGS. 1A and 1Bin an unfolded state. The unfolded state is formed by folding variouscomponents (circuit portions) of flexible interconnect circuit 100. Theunfolded state may be also referred to as an as-installed state, todifferentiate from the as-manufactured state (the folded state). If arectangular boundary (e.g., representing a sheet used for the circuitfabrication) is drawn around flexible interconnect circuit 100 in thepre-folded state (which may be referred to as a pre-folded footprint)and, separately, around flexible interconnect circuit 100 in theunfolded state (which may be referred to as an unfolded footprint), thenthe area of the unfolded state boundary will be much larger (e.g., 25%larger, 50% larger, or even 100% larger) than the area of the pre-foldedstate boundary. This boundary area comparison illustrates thecorresponding reduction of the material waste associated withmanufacturing flexible interconnect circuit 100 in the pre-folded state.Furthermore, folding flexible interconnect circuit 100 allows neworientations of conductive leads in flexible interconnect circuit 100(e.g., a crossover of conductive leads in the folded state). It shouldbe noted that the crossover of conductive leads is not possible in thepre-folded state since all conductive leads in the same layer are formedfrom the same sheet of metal as further described below with referenceto FIG. 1C.

Referring to FIGS. 1A and 1B, flexible interconnect circuit 100comprising first circuit portion 111 and second circuit portion 112.First circuit portion 111 and second circuit portion 112 aremonolithically integrated by various shared components of flexibleinterconnect circuit 100 as further described below. First circuitportion 111 and second circuit portion 112 are identified by a foldingpattern, e.g., a folding line extending between first circuit portion111 and second circuit portion 112. Various folding lines are identifiedin FIGS. 1A and 1B with dashed lines. The example of the folding linebetween first circuit portion 111 and second circuit portion 112 ispresented in an expanded view, provided between FIGS. 1A and 1B. Thefolding pattern/lines, which are shown in FIG. 1A, defines first circuitportion 111, second circuit portion 112, third circuit portion 113,fourth circuit portion 114, fifth circuit portion 115, sixth circuitportion 116, and seventh circuit portion 117. However, one havingordinary skill in the art would understand that any folding patterns andany number of circuit portions are within the scope.

In some examples, a folding line extends to a slit corner. For example,various slits can be provided in flexible interconnect circuit 100 tofacilitate the folding of different circuit portions relative to eachother. Specifically, FIG. 1A illustrates an example of flexibleinterconnect circuit 100 comprising first slit 105 (extending betweensecond circuit portion 112 and third circuit portion 113), second slit106 (extending between fourth circuit portion 114 and a combination ofthird circuit portion 113 and fifth circuit portion 115), and third slit107 (extending between sixth circuit portion 116 and seventh circuitportion 117). One having ordinary skill in the art would understand thatflexible interconnect circuit 100 can have any number of slits or noslits at all. For example, a single continuous strip with no slits thatbe folded one or more times (e.g., to change the direction) as shown bythird circuit portion 113 and fifth circuit portion 115. A slit allowsbranching out of circuit portions. For example, first circuit portion111 extends to first slit 105, at which point first circuit portion 111branches out into second circuit portion 112 and third circuit portion113.

Referring to FIGS. 1A-1C, flexible interconnect circuit 100 in apre-folded state is defined by first side 103 and second side 104. Firstside 103 is formed by first insulating layer 151, while second side 104is formed by second insulating layer 152. In some examples, firstinsulating layer 151 is continuous or, more specifically, monolithic forthe entire flexible interconnect circuit 100 and can be referred to asthe first monolithic insulating layer. Similarly, second insulatinglayer 152 can be continuous or, more specifically, monolithic for theentire flexible interconnect circuit 100 and can be referred to as thesecond monolithic insulating layer. First insulating layer 151 andsecond insulating layer 152 are bonded together, e.g., laminated, usingan adhesive. In some examples, flexible interconnect circuit 100comprises one or more additional insulating and/or adhesive layerspositioned first insulating layer 151 and second insulating layer 152.Referring to FIG. 1C, flexible interconnect circuit 100 also comprisesconductive traces 150, which are positioned and sealed (from theenvironment) between first insulating layer 151 and second insulatinglayer 152. In some examples, each of first circuit portion 111 andsecond circuit portion 112 comprises at least one of conductive traces150.

As such, each of first circuit portion 111 and second circuit portion112 comprises first side 103 and second side 104, with second side 104being opposite to first side 103. Specifically, first side 103 of firstcircuit portion 111 and first side 103 of second circuit portion 112 isformed by first insulating layer 151. In some examples, first insulatinglayer 151 forms first side 103 of the entire flexible interconnectcircuit 100, e.g., first side 103 of all portions of flexibleinterconnect circuit 100 is formed by first insulating layer 151. Assuch, all portions of flexible interconnect circuit 100 aremonolithically integrated by various components of flexible interconnectcircuit 100, e.g., first insulating layer 151, second insulating layer152, and conductive traces 150. Second side 104 of first circuit portion111 and second side 104 of second circuit portion 112 is formed bysecond insulating layer 152.

First insulating layer 151 and second insulating layer 152 provideelectrical isolation and mechanical support to conductive traces 150. Insome examples, first insulating layer 151 and second insulating layer152 may initially be processed in a sheet or roll form and maysubsequently be laminated to the conductive layer using, for example,adhesive material. First insulating layer 151 and second insulatinglayer 152 may include (or be formed from) polyimide (PI), polyethylenenaphthalate (PEN), polyethylene terephthalate (PET), polymethylmethacrylate (PMMA), ethyl vinyl acetate (EVA), polyethylene (PE),polyvinyl fluoride (PVF), polyamide (PA), and/or polyvinyl butyral(PVB). Additional aspects (e.g., thicknesses) of first insulating layer151 and second insulating layer 152 are described below.

In some examples, conductive traces 150 have a uniform thicknessthroughout the entire circuit boundary. For example, conductive traces150 can be formed from the same sheet of metal. More specifically,different (disjoint) portions of conductive traces 150 can be formedfrom the same sheet of metal. In some examples, all conductive traces150 are formed from the same material, e.g., aluminum, copper, or thelike. The use of aluminum (instead of copper) may help with lowering theoverall circuit weight and also with lowering the minimum achievablefuse current rating. Specifically, aluminum has a higher resistivity andlower melting temperature than copper. As such, forming fusible links inan aluminum conductive layer may allow for more precise control of thefusible parameters (for the same size tolerance). In general, conductivetraces 150 may be formed from any conductive material that issufficiently conductive (e.g., a conductivity being greater than10{circumflex over ( )}6 S/m or even greater than 10{circumflex over( )}7 S/m to allow for current flow through the foil with low powerloss.

In some examples, conductive traces 150 may include a surface sublayeror coating for providing a low electrical contact resistance and/orimproving corrosion resistance. The surface sublayer may assist withforming electrical interconnections using techniques/materialsincluding, but not limited to, soldering, laser welding, resistancewelding, ultrasonic welding, bonding with conductive adhesive, ormechanical pressure. Surface sublayers that may provide a suitablesurface for these connection methods include, but are not limited to,tin, lead, zinc, nickel, silver, palladium, platinum, gold, indium,tungsten, molybdenum, chrome, copper, alloys thereof, organicsolderability preservative (OSP), or other electrically conductivematerials. Furthermore, the surface sublayer may be sputtered, plated,cold-welded, or applied via other means. In some examples, the thicknessof the surface sublayer may range from 0.05 micrometers to 10micrometers or, more specifically, from 0.1 micrometers to 2.5micrometers. Furthermore, in some examples, the addition of a coating ofthe OSP on top of the surface sublayer may help prevent the surfacesublayer itself from oxidizing over time. The surface sublayer may beused when a base sublayer of conductive traces 150 includes aluminum orits alloys. Without protection, exposed surfaces of aluminum tend toform a native oxide, which is insulating. The oxide readily forms in thepresence of oxygen or moisture. To provide a long-term stable surface inthis case, the surface sublayer may be resistant to the in-diffusion ofoxygen and/or moisture. For example, zinc, silver, tin, copper, nickel,chrome, or gold plating may be used as surface layers on analuminum-containing base layer.

Referring to FIG. 1C, conductive traces 150 can be arranged in either asingle layer or multiple layers. In some examples, conductive traces 150in different layers are interconnected within flexible interconnectcircuit 100. Furthermore, conductive traces 150 in the same layer can beinterconnected or even monolithic with each other. It should be notedthat conductive traces 150 in the same layer can be formed from the samesheet of metal.

In some examples, a circuit portion has a corresponding connector, e.g.,attached at a free end of this portion. For example, first circuitportion 111 terminates with first connector 121, second circuit portion112 terminates with second connector 122, fourth circuit portion 113terminates with third connector 123, seventh circuit portion 117terminates with fourth connector 124, and sixth circuit portion 116terminates with fifth connector 125. Conductive traces 150 in eachcircuit portion can be electrically coupled to the conductive leads ofthe corresponding connector. Furthermore, conductive traces 150 of onecircuit portion can extend into another circuit portion. For example, atrace can start at first connector 121 (e.g., connected to a connectorterminal in first connector 121) and extend through first circuitportion 111, third circuit portion 113, fifth circuit portion 115, andsixth circuit portion 116 eventually ending at fifth connector 125(e.g., connected to a connector terminal in fifth connector 125). Assuch, this conductive trace interconnects the connector terminals infirst connector 121 and fifth connector 125).

The relative positions of circuit portions depend on the folding stateof flexible interconnect circuit 100. For example, FIGS. 1A and 1Billustrate flexible interconnect circuit 100 in a pre-folded state. Inthis state/example, all circuit portions extend along the samedirection, e.g., parallel to each other/along primary axis 108 offlexible interconnect circuit 100. As noted above, the manufacturing offlexible interconnect circuit 100 in this configuration/state helps tominimize material waste. However, other configurations where circuitportions (while in the pre-folded state) are not all parallel to eachother are also within the scope. The pre-folded design is determinedbased on the unfolded design requirements, folding options, and otherfactors. Furthermore, all circuit portions can be coplanar in thispre-folded state and do nor overlap and stack. Finally, first sides 103of all circuit portions face in the same direction (e.g., up in FIG. 1Aand down in FIG. 1B) in this pre-folded state. Similarly, second sides104 of all circuit portions face in the same direction (e.g., down inFIG. 1A and up in FIG. 1B) in this pre-folded state.

When interconnect circuit 100 is folded (from a pre-folded state to anunfolded state), one or more circuit portions change their respectiveorientation, e.g., as schematically shown in FIG. 1D. In the illustratedexample, second circuit portion 112 is folded 90° relative to firstcircuit portion 111. In other words, first circuit portion 111 is nolonger parallel to second circuit portion 112. Any folding angle greaterthan 0° is within the scope (e.g., between 0° and 180° or, morespecifically, between 20° and 160°, or even between 30° and 150°). Itshould be noted that during this folding, second circuit portion 112 isalso flipped relative to first circuit portion 111. Specifically, FIG.1D illustrates that first side 103 of first circuit portion 111 andsecond side 104 of second circuit portion 112 are now facing up. Theremaining portions are folded similarly, e.g., third circuit portion 113is folded 90° relative to first circuit portion 111 but in a differentdirection than second circuit portion 112. As such, in the unfoldedstate, third circuit portion 113 and second circuit portion 112 extendin different directions. Each fourth circuit portion 114 and fifthcircuit portion 115 is folded 90° relative to third circuit portion 113but in different directions. It should be noted that since (a) thirdcircuit portion 113 is folded relative to first circuit portion 111 and(b) each of fourth circuit portion 114 and fifth circuit portion 115 isfolded relative to third circuit portion 113, first side 103 of firstcircuit portion 111 and first side 103 of each of fourth circuit portion114 and fifth circuit portion 115 are facing in the same direction(i.e., up in FIG. 4D). Sixth circuit portion 116 is folded 90° relativeto fifth circuit portion 115. Finally, seventh circuit portion 117 isfolded 90° relative to sixth circuit portion 116. The folding patterndepends on the desired routing of each circuit portion, the position ofeach connector, and other factors associated with the installation andapplication of interconnect circuit 100.

Furthermore, the folding creates a folding corner where first circuitportion 111 and second circuit portion 112 collective form stack 109,which is schematically shown in FIG. 1E. Specifically, in this stack109, second side 104 of first circuit portion 111 and second side 104 ofsecond circuit portion 112 face in opposite directions. Similarly, firstside 103 of first circuit portion 111 and first side 103 of secondcircuit portion 112 face in opposite directions. Furthermore, withinstack 109, first side 103 of first circuit portion 111 and first side103 of second circuit portion 112 face each other and even interfacewith each other (e.g., glued to each other to preserve thisorientation). The same or similar corners exist at each fold.

Referring to FIGS. 2A and 2B, flexible interconnect circuit assembly 190comprises bonding film 130 attached to second side 104 of first circuitportion 111 and first side 103 of second circuit portion 112. The side,which is attached to bonding film 130, of each circuit portion dependson the folding pattern. Overall, all sides facing in one direction canbe attached to bonding film 130. In some examples, all circuit portionsat least partially overlap and are attached to bonding film 130.Alternatively, some circuit portions can be positioned away from bondingfilm 130 (not shown in FIG. 2A), e.g., extend outside the boundary ofbonding film 130. Within flexible interconnect circuit assembly 190,bonding film 130 is used to support at least some circuit portions inthe unfolded state, e.g., with additional support provided by temporarysupport film 140. Later, when flexible interconnect circuit assembly 190is installed, bonding film 130 is used to support at least some circuitportions in the same unfolded state and attach these circuit portions toa base structure as further described below with reference to FIGS.7A-7C.

In some examples, bonding film 130 comprises a base layer and anadhesive layer. Some examples of suitable materials for the base layerinclude but are not limited to polyimide (PI), polyethylene naphthalate(PEN), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA),ethyl vinyl acetate (EVA), polyethylene (PE), polyvinyl fluoride (PVF),polyamide (PA), and/or polyvinyl butyral (PVB). In some examples, thethickness of bonding film 130 is between micrometers and 200 micrometersor, more specifically, between 20 micrometers and 50 micrometers. Someexamples of suitable materials for the adhesive layer include, but arenot limited to, a pressure-sensitive adhesive. Bonding film 130 can besufficiently flexible to conform to the shape of flexible interconnectcircuit 100 when supporting flexible interconnect circuit 100 ontemporary support film 140, e.g., as shown in FIGS. 3B and 3C, and alsowhen supporting flexible interconnect circuit 100 on base structure 199as, e.g., is schematically shown in FIG. 7C.

The adhesive layer faces flexible interconnect circuit 100 and bonds tocircuit portions, e.g., a part of first circuit portion 111 and a partof second circuit portion 112. In some examples, another part of firstcircuit portion 111 (e.g., the part adjacent to first connector 121)extends outside the boundary bonding film 130. In some examples, allconnectors are positioned and parts of circuit portions extending tothese connectors extend outside the boundary bonding film 130. Thisfeature provides some flexibility to the connectors when flexibleinterconnect circuit assembly 190 is attached to a base structure.

Bonding film 130 extends past the edges of circuit portions therebyforming adhesive flaps for connecting a base structure. In someexamples, the width (W) of these adhesive flaps is between millimetersand 50 millimeters or, more specifically, between 5 millimeters and 20millimeters. Adhesive flaps can extend past one or both edges of circuitportions, e.g., as shown in FIG. 2A and FIG. 2B.

Referring to FIGS. 3A-3C, flexible interconnect circuit assembly 190comprises temporary support film 140 attached to bonding film 130.Temporary support film 140 is used to support flexible interconnectcircuit 100 prior to installation of faces interconnect circuit 100 on abase structure. During this installation, temporary support film 140 isremoved and is not a part of the final assembly. Some examples ofsuitable materials for temporary support film 140 include but are notlimited to polyimide (PI), polyethylene naphthalate (PEN), polyethyleneterephthalate (PET), polymethyl methacrylate (PMMA), ethyl vinyl acetate(EVA), polyethylene (PE), polyvinyl fluoride (PVF), polyamide (PA),and/or polyvinyl butyral (PVB).

Temporary support film 140 covers the entire boundary of interconnectcircuit 100 and can have a rectangular shape, e.g., to simplify handlingand storage. In some examples, temporary support film 140 multiple facesinterconnect circuits 100, e.g., as shown in FIG. 4A. Furthermore,flexible interconnect circuit assembly 190 can be formed into a roll,e.g., as shown in FIG. 4B. In some examples, flexible interconnectcircuit assembly 190 can comprise interconnect circuits 100 havingdifferent designs.

Referring to the cross-sectional view in FIGS. 3B-3D, flexibleinterconnect circuit 100 at least partially extends between temporarysupport film 140 and bonding film 130. For example, FIG. 3B illustratesfirst side 103 of first circuit portion 111 facing temporary supportfilm 140. FIG. 3C illustrates second side 104 of second circuit portion112 facing temporary support film 140. FIG. 3D illustrates fifth circuitportion 115 forming stack 109 with third circuit portion 113 and anotherstack 109 with sixth circuit portion 116. It should be noted that thethickness of stack 109 is twice the thickness of each circuit portion.As such, in some parts, bonding film 130 directly interfaces temporarysupport film 140 (e.g., away from circuit portions), spaced apart by asingle circuit-portion thickness, or spaced apart by a doublecircuit-portion thickness. The flexibility of bonding film 130 ensuresconformal coverage and minimal gaps at circuit-portion edges.

As shown in FIG. 3A, first circuit portion 111 terminates with firstconnector 121. First connector 121 and a part of first circuit portion111 adjacent to first connector 121 extend outside the boundary ofbonding film 130. As described above, this extension providesflexibility to first connector 121 when flexible interconnect circuitassembly 190 is installed. In more specific examples, first connector121 and portion of first circuit portion 111 adjacent to first connector121 overlap boundary of with temporary support film 140. In someexamples, first connector 121 may be temporarily attached to temporarysupport film 140, e.g., to maintain the position of first connector 121during handling of flexible interconnect circuit assembly 190 (e.g.,forming a roll from flexible interconnect circuit assembly 190).

FIG. 5 : Examples of Forming Flexible Interconnect Circuit Assemblies

FIG. 5 is a process flowchart corresponding to method 500 of forming aflexible interconnect circuit assembly 190, in accordance with someexamples. Method 500 comprises (block 510) providing flexibleinterconnect circuit 100 comprising first circuit portion 111 and secondcircuit portion 112 monolithically integrated with first circuit portion111. Flexible interconnect circuit 100 is provided in a pre-foldedstate, various examples of which are described above with reference toFIGS. 1A-1C. For example, each of first circuit portion 111 and secondcircuit portion 112 is an elongated structure extending parallel toprimary axis 108 of flexible interconnect circuit 100, e.g., as shown inFIGS. 1A and 1B. Each of first circuit portion 111 and second circuitportion 112 comprises first side 103 and second side 104, which isopposite first side 103. At this pre-folded stage, first side 103 offirst circuit portion 111 and first side 103 of second circuit portion112 face in the same direction. Similarly, second side 104 of firstcircuit portion 111 and second side 104 of second circuit portion 112face in the same direction. In some examples, before folding, firstcircuit portion 111 and second circuit portion 112 are coplanar.

Method 500 comprises (block 520) folding second circuit portion 112relative to first circuit portion 111 as, e.g., is schematically shownin FIG. 1D. In general, this folding of various circuit portions may bereferred to as the folding of flexible interconnect circuit 100 into theinstallation shape. Upon completion of this operation, flexibleinterconnect circuit 100 is in an unfolded state/installation shape.More specifically, second circuit portion 112 is no longer parallel toprimary axis 108 of flexible interconnect circuit 100. More generally,the orientation of second circuit portion 112 relative to first circuitportion 111 is changed during this operation. Furthermore, first side103 of first circuit portion 111 and first side 103 of second circuitportion 112 face in opposite directions after folding as, e.g., isschematically shown in FIG. 1E. It should be noted that other circuitportions can be folded in the same operation, e.g., as schematicallyshown in FIG. 1D.

In some examples, after folding, a part of first side 103 of firstcircuit portion 111 directly interfaces a part of first side 103 ofsecond circuit portion 112, e.g., as shown in FIG. 1E. Alternatively, apart of second side 104 of first circuit portion 111 can directlyinterface a part of second side 104 of second circuit portion 112 (e.g.,if second circuit portion 112 is folded in a different directionrelative to first circuit portion 111). In some examples, theseinterfacing parts are glued to each other, e.g., to preserve the fold.

Method 500 comprises (block 530) attaching bonding film 130 to secondside 104 of first circuit portion 111 and first side 103 of secondcircuit portion 112 as, e.g., is schematically shown in FIGS. 2A and 2B.For example, bonding film 130 can be laminated to flexible interconnectcircuit 100. In some examples, bonding film 130 is initially attached asa larger component, which is later cut based on the folded shape offlexible interconnect circuit 100. It should be that when bonding film130 is attached to flexible interconnect circuit 100, portions offlexible interconnect circuit 100 can extend past the boundaries ofbonding film 130. Furthermore, it should be noted portions of bondingfilm 130 extend past the boundaries of flexible interconnect circuit 100thereby creating adhesive flaps.

Method 500 comprises (block 540) attaching temporary support film 140 tobonding film 130 such that first side 103 of first circuit portion 111and second side 104 of second circuit portion 112 faces temporarysupport film 140 as, e.g., is schematically shown in FIGS. 3A-3D. Assuch a portion of flexible interconnect circuit 100 is positionedbetween temporary support film 140 and bonding film 130. Furthermore,all adhesive flaps of bonding film 130 can be covered by temporarysupport film 140 after this operation thereby not leaving any exposedadhesive surfaces. When temporary support film 140 is removed fromflexible interconnect circuit assembly 190 at later operations, theseadhesive flaps are exposed again for bonding to various panels, e.g., asfurther described below with reference to FIG. 6 .

In some examples, method 500 comprises (block 550) arranging flexibleinterconnect circuit assembly 190 into a shipping configuration selectedfrom the group consisting of a planar sheet and a roll. In someexamples, flexible interconnect circuit assembly (e.g., formed into aroll) comprises additional flexible interconnect circuits.

FIGS. 6 and 7A-7C: Examples of Installing Flexible Interconnect CircuitAssemblies

FIG. 6 is a process flowchart corresponding to method 600 of installingflexible interconnect circuit assembly 190 onto base structure 199, inaccordance with some examples. FIGS. 7A-7C are schematic illustrationsof different stages during method 600. Various examples of basestructure 199 are within the scope, such as a car panel (e.g., a doorpanel) as shown in FIG. 7C.

Method 600 may commence with (block 610) removing temporary support film140, thereby exposing parts of the adhesive surface of bonding film 130,e.g., as shown in FIG. 7A. These exposed adhesive surfaces can bereferred to as adhesive flaps and are used for adhering flexibleinterconnect circuit assembly 190 onto base structure 199. For example,bonding film 130 can comprise a pressure-sensitive adhesive surface.Furthermore, it would be noted that temporary support film 140, onceremoved in this operation, can be reused in the process described inFIG. 5 .

Method 600 proceeds with (block 620) pressing this adhesive surfaceagainst base structure 199 thereby attaching flexible interconnectcircuit assembly 190 to base structure 199, e.g., as shown in FIG. 7B. Apart of flexible interconnect circuit 100 is positioned between bondingfilm 130 and base structure 199 and is supported by bonding film 130relative to base structure 199. In some examples, flexible interconnectcircuit assembly 190 comprises various aligning features (e.g.,marks/cuts on bonding film 130 and/or flexible interconnect circuit 100to determine the position of flexible interconnect circuit assembly 190relative to base structure 199.

FIGS. 8A-8C, 9A-9C, 10A-10F, and 11 : Examples of Folded FlexibleInterconnect Circuits

Referring to FIG. 8A-8C, in some examples, flexible interconnect circuit100 comprises first insulating layer 151, second insulating layer 152,and conductive traces 150. Conductive traces 150 are positioned betweenfirst insulating layer 151 and second insulating layer 152 such thatfirst insulating layer 151 and second insulating layer 152 are bondedtogether around conductive traces 150. Various examples of firstinsulating layer 151, second insulating layer 152, and conductive traces150 are described above.

Flexible interconnect circuit 100 also comprises adhesive layer 160,interfacing and covering second insulating layer 152 such that secondinsulating layer 152 is positioned between first insulating layer 151.First insulating layer 151, second insulating layer 152, and adhesivelayer 160 form stack 170 comprising first stack portion 171, secondstack portion 172, and flap portion 173. FIGS. 8A and 8B illustrateflexible interconnect circuit 100 in a pre-folded state. In this state,first stack portion 171, second stack portion 172, and flap portion 173are coplanar. FIG. 8C illustrates flexible interconnect circuit 100 in afolded state. In this state, first stack portion 171 and second stackportion 172 overlap with each other, effectively forming a secondarystack. It should be noted that in this state, flap portion 173 does notoverlap with either first stack portion 171 or second stack portion 172.Instead, flap portion 173 extends away from the secondary stack (formedby first stack portion 171 and second stack portion 172) and isavailable for bonding to other structures.

Referring to FIG. 8C, adhesive layer 160 in first stack portion 171interfacing and adhered to adhesive layer 160 in second stack portion172. This adhesive-adhesive interface preserves the shape of thesecondary stack (formed by first stack portion 171 and second stackportion 172). Furthermore, adhesive layer 1360 in flap portion 173extends past first stack portion 171 and second stack portion 172. Thisadhesive layer 160 in flap portion 173 is available for bonding toexternal structures.

Referring to FIG. 8C, in some examples, adhesive layer 160 of flapportion 173 is covered by temporary liner 162. Temporary liner 162allows handling and transporting flexible interconnect circuit 100 andpreserving the surface of adhesive layer 160. When flexible interconnectcircuit 100 is installed, temporary liner 162 is removed, and adhesivelayer 160 of flap portion 173 is exposed.

In some examples, flap portion 173 is free from conductive traces 150.This feature improves the flexibility of flap portion 173. Furthermore,the flexibility of flap portion 173 can be further improved by extendingonly one of first insulating layer 151 and second insulating layer 152into flap portion 173. Furthermore, flap portion 173 can have neitherfirst insulating layer 151 and second insulating layer 152. Instead,adhesive layer 160 comprises its own base layer (e.g., attached to firstinsulating layer 151 and second insulating layer 152), on which theadhesive is deposited. Alternatively, flap portion 173 comprises bothfirst insulating layer 151 and second insulating layer 152. In morespecific examples, flap portion 173 also comprises one or moreconductive traces 150 (not shown in FIG. 8C). In some examples, theflexibility of flap portion 173 is increased by providing various cutfeatures at the interface of flap portion 173 and stack 170 and/orwithin flap portion 173. In some examples, the width of flap portion 173(in the X direction in FIG. 8C) is between 5 millimeters and 70millimeters or, more specifically, between 10 millimeters and 50millimeters.

While FIG. 8A illustrates flap portion 173 being a continuous structureforming the entire first edge 101 of flexible interconnect circuit 100,other examples are also within the scope. For example, FIG. 9Aillustrates an example of flexible interconnect circuit 100 wherein flapportions 173 are discontinuous patches. The “A-A” cross-section (shownin FIG. 9B) represents the part of flexible interconnect circuit 100where flap portion 173 is present. The “B-B” cross-section (shown inFIG. 9C) represents the part of flexible interconnect circuit 100 whereflap portion 173 is not present. This flap “cutout” can be used to clearvarious features on the base structure during the installation offlexible interconnect circuit 100 onto this base structure.

Furthermore, flap portions 173 can form different (opposite) edges offlexible interconnect circuit 100, e.g., as schematically shown in FIGS.10A-10F. This approach allows positioning adhesive layer 160 ondifferent sides of flexible interconnect circuit 100 during the initialfolding of flexible interconnect circuit 100 (in the initial foldedstage that is schematically shown in FIGS. 10C and 10E). When flexibleinterconnect circuit 100 is later unfolded (e.g., by further folding acircuit portion as described above with references to FIGS. 1A-1E andschematically shown by FIGS. 10E and 10F herein), adhesive layer 160 ispositioned on the same side (e.g., shown in FIGS. 10C and 10F). Thisunfolding of flexible interconnect circuit 100 is also schematicallyshown in FIG. 11 with the position of adhesive layer 160 identified.Alternatively, adhesive layer 160 can remain positioned on differentsides, e.g., for installation on complex objects/surfaces.

FIG. 12 : Examples of Forming Folded Flexible Interconnect Circuits

FIG. 12 is a process flowchart corresponding to method 1200 formingflexible interconnect circuit 100, in accordance with some examples.Various examples of flexible interconnect circuit 100 are describedabove with reference to FIGS. 9A-11 .

In some examples, method 1200 comprises (block 1210) providing stack 170formed by first insulating layer 151, second insulating layer 152,conductive traces 150, and adhesive layer 1360. As described above andshown with reference to FIGS. 8A and 8B, conductive traces 150 arepositioned between first insulating layer 151 and second insulatinglayer 152 such that first insulating layer 151 and second insulatinglayer 152 are bonded together around conductive traces 150. Adhesivelayer 160 interfaces and covers second insulating layer 152 such thatsecond insulating layer 152 is positioned between first insulating layer151. Stack 170 comprises first stack portion 171, second stack portion172, and flap portion 173. At this stage, stack 170 is in a pre-foldedstate as, e.g., is schematically shown in FIGS. 8A and 8B. In thisstate, first stack portion 171, second stack portion 172, and flapportion 173 can be coplanar.

In some examples, method 1200 comprises (block 1220) folding stack 170such that first stack portion 171 and second stack portion 172 overlapand adhesive layer 160 in first stack portion 171 interfacing andadhered to adhesive layer 160 in second stack portion 172 as, e.g., isschematically shown in FIG. 8C. Adhesive layer 160 in flap portion 173extends past first stack portion 171 and second stack portion 172.

FIG. 13A-14B: Examples of Connector-Support Portions

FIG. 13A is a cross-sectional side view of flexible interconnect circuit100 comprising connector-support portion 1350, in accordance with someexamples. A portion of flexible interconnect circuit 100 withoutconnector-support portion 1350 can be referred to as primary portion1305. Connector-support portion 1350 is attached to primary portion 1305of flexible interconnect circuit 100, e.g., at each end of primaryportion 1305 that receives a connector. Connector-support portion 1350provides additional mechanical support to this end of primary portion1305 when the connector is attached to the end as further describedbelow with reference to FIGS. 14A and 14B.

Flexible interconnect circuit 100 or, more specifically, primary portion1305 comprises first insulating layer 151, second insulating layer 152,and conductive layer 1330. Conductive layer 1330 is partially positionedbetween first insulating layer 151 and second insulating layer 152(e.g., away from the ends of primary portion 1305). Conductive layer1330 comprises one or more conductive traces 150, which may be alsoreferred to as conductive leads. For example, FIG. 13B illustrates eightconductive traces 150. However, any number of conductive traces 150 arewithin the scope. In some examples, the number of conductive traces 150extending to a particular end of primary portion 1305 depends on thenumber of conductive elements in the connector attached to this end. Ina flexible interconnect assembly, conductive traces 150 form individualelectrical connections to corresponding conductive elements of theconnector attached to this end.

The thickness of one or both first insulating layer 151 and secondinsulating layer 152 may be between 1 micrometer and 500 micrometers or,more specifically, between 10 micrometers and 125 micrometers. In someexamples, each of first insulating layer 151 and second insulating layer152 includes an adhesive sublayer facing conductive layer 1330, e.g.,for lamination to conductive layer 1330 and also to each other. Theseadhesive sublayers may be also used for directly laminating firstinsulating layer 151 and second insulating layer 152 (beyond theconductive layer boundaries), e.g., for edge sealing of flexibleinterconnect circuit 100. In some examples, the surface of firstinsulating layer 151 and/or second insulating layer 152 (e.g., thesurface facing away from conductive layer 1330) comprises an adhesivesublayer for bonding this insulating layer to an external structure(e.g., a supporting panel). First insulating layer 151 and secondinsulating layer 152 provide the electrical isolation and mechanicalsupport to conductive layer 1330. Additional aspects (e.g., materials)of first insulating layer 151 and second insulating layer 152 aredescribed elsewhere in this document. Furthermore, additional aspects ofconductive traces 150 or, more generally, conductive layer 1330 formedby these traces are described elsewhere in this document (e.g., uniformthickness, materials, surface sublayers).

One or more conductive traces 150 comprises exposed portion 1331extending past at least first insulating layer 151 as, e.g., isschematically shown in FIGS. 1A and 1B. Exposed portion 1331 ofconductive traces 150 allows forming of electrical connections betweenthese conductive traces 150 and the corresponding conductive elements ofthe connector. In some examples, exposed portion 1331 is between 0.5millimeters and 5 millimeters long (in the X-direction) or, morespecifically, between 1 millimeter and 3 millimeters long.

In some examples, exposed portion 1331 comprises contact interface layer1332 forming exposed surface 1333 (which directly interfaces withconductive elements of the connector). For example, contact interfacelayer 1332 is formed with electroless nickel immersion gold (ENIG).Specifically, contact interface layer 1332 can be formed over a baselayer of conductive traces 150, with the base layer formed from copper,aluminum, and the like. Contact interface layer 1332 is used to reducethe oxidation and improve the solderability of the base layer. Contactinterface layer 1332 can be formed by electroless nickel plating of thebase layer followed by immersion in a solution comprising agold-containing salt. During this immersion process, a portion of nickelis oxidized, while the gold ions are reduced to a metallic state anddeposited on the surface. In some examples, palladium is used inaddition to or instead of gold.

Referring to FIG. 13A, in some examples, connector-support portion 1350comprises reinforcement metal layer 1370 and is attached to secondinsulating layer 152. Various forms of attachments are within the scope.For example, connector-support portion 1350 can comprise adhesive layer1360, interfacing with second insulating layer 152. More specifically,adhesive layer 1360 is positioned between reinforcement metal layer 1370and second insulating layer 152 thereby attaching connector-supportportion 1350 to second insulating layer 152. For example, adhesive layer1360 comprises a pressure-sensitive adhesive. In the same or anotherexample, adhesive layer 1360 comprises double-sided adhesive tape. Thethickness of adhesive layer 1360 can be between micrometers and 250micrometers or, more specifically, between 50 micrometers and 200micrometers.

As noted above, connector-support portion 1350 comprises reinforcementmetal layer 1370. Reinforcement metal layer 1370 provides mechanicalreinforcement to flexible interconnect circuit 100 when flexibleinterconnect circuit 100 is attached to a connector as further describedbelow with reference to FIGS. 14A and 14B. For example, reinforcementmetal layer 1370 can engage the connector helping to improve thepull-out strength of the attachment between flexible interconnectcircuit 100 and the connector. Reinforcement metal layer 1370 can be inthe form of a metal plate or foil. In some examples, reinforcement metallayer 1370 comprises one or more of aluminum (e.g., hardened aluminumsuch as 1350-H19) and stainless steel. The thickness (T1) ofreinforcement metal layer 1370 can be between 20 micrometers and 200micrometers or, more specifically, between 40 micrometers and 150micrometers or even between 50 micrometers and 100 micrometers. Acombination of these features of reinforcement metal layer 1370 helpedto significantly improve (e.g., by 20%) the connector retention force incomparison to conventional flexible circuits (i.e., the force along theX-axis).

Referring to FIG. 13A, connector-support portion 1350 at least partiallyoverlaps with exposed portion 1331. More specifically, connector-supportportion 1350 can fully overlap with exposed portion 1331. For purposesof this disclosure, the term “overlap” means the corresponding alignmentof X-Y footprints of different components, e.g., comparing the Z-axisprojections of different components. These overlaps ensure the supportof exposed portion 1331 relative to the rest of flexible interconnectcircuit 100 and also the support of exposed portion 1331 relative to theconnector to which this exposed portion 1331 is attached. Specifically,exposed portion 1331 is inserted into a connector to form electricalconnections between conductive traces 150 and conductive elements of theconnector as further described below with reference to FIGS. 2A and 2B.As such, connector-support portion 1350 is also partially inserted intothe connector. Connector-support portion 1350 mechanically engages theconnector. In some examples, the length (L2) of connector-supportportion 1350 (in the X-direction) is between 5 millimeters and 30millimeters or, more specifically, between 10 millimeters and 20millimeters.

In some examples, connector-support portion 1350 at least partiallyoverlaps with first insulating layer 151. The length (L1) of thisoverlap portion can be between 3 millimeters and 25 millimeters or, morespecifically, between 5 millimeters and 17 millimeters. Furthermore, theentire connector-support portion 1350 can overlap with second insulatinglayer 152 as, e.g., is schematically shown in FIG. 1A.

In some examples, connector-support portion 1350 further comprisesprotective layer 1375 such that reinforcement metal layer 1370 ispositioned between protective layer 1375 and second insulating layer152. Protective layer 1375 isolates reinforcement metal layer 1370 fromthe environment, e.g., when forming contact interface layer 1332.Protective layer 1375 can comprise one or more polyimide (PI),polyethylene naphthalate (PEN), polyethylene terephthalate (PET),polymethyl methacrylate (PMMA), ethyl vinyl acetate (EVA), polyethylene(PE), polyvinyl fluoride (PVF), polyamide (PA), and/or polyvinyl butyral(PVB). The thickness of protective layer 1375 can be between 5micrometers and 100 micrometers or, more specifically, between 10micrometers and 50 micrometers. It should be noted that protective layer1375 is optional. In some examples, e.g., shown in FIG. 1C,connector-support portion 1350 does not have a protective layer. Inthese examples, reinforcement metal layer 1370 is exposed. Furthermore,in these examples, contact interface layer 1332 can be formed beforeattaching connector-support portion 1350 to primary portion 1305 offlexible interconnect circuit 100.

Referring to FIG. 13B, in some examples, flexible interconnect circuit100 comprises notches 1340 used for engaging a connector as furtherdescribed below with reference to FIGS. 14A and 14B. For example,notches 1340 can be positioned on side edges (e.g., first edge 101 andsecond edge 102) of flexible interconnect circuit 100. For purposes ofthis disclosure, the side edges are defined as edges that extend to theend of flexible interconnect circuit 100, which is inserted into aconnector. Leading edge 1301 extends between the two side edges and isdefined as an edge that is inserted into the connector. Notches 1340extend at least through reinforcement metal layer 1370 ofconnector-support portion 1350. In some examples, notches 1340 extendthrough all components (layers) of connector-support portion 1350.Furthermore, notches 1340 can extend through one or more components ofprimary portion 1305, e.g., second insulating layer 152.

As noted above, notches 1340 are used for engaging a connector or, morespecifically, retention pins 1385 of connector 1380, e.g., asschematically shown in FIG. 14B. As such, the size of notches 1340 andrelative positions (e.g., relative to leading edge 1301) are determinedby the connector specifications. Referring to FIG. 13B, in someexamples, the depth (DO) of notches 1340 is between about 0.2millimeters and 1.5 millimeters or, more specifically, between 0.4millimeters and 0.8 millimeters. The width (WO) of notches is betweenabout 1 millimeter and 5 millimeters or, more specifically, between 2millimeters and 4 millimeters. In some examples, the width (W2) of theleading edge, which is inserted into a connector, is between 5millimeters and 50 millimeters or, more specifically, between 7millimeters and 20 millimeters. The width of the leading edge may dependon the number of conductive traces 150, expecting this edge. Forexample, FIG. 13B illustrates eight conductive traces 150 extending tothe leading edge. However, any number is within the scope, e.g., one,two, three, four, and so on. In some examples, the number can be 6, 8,10, 20, 25, 30, 35, 40, 45, 50, 55, and 60.

FIG. 14A is a cross-sectional side view of flexible interconnectassembly 190 utilizing flexible interconnect circuit 100, variousexamples of which are described above with reference to FIGS. 1A-1C.FIG. 14B is a top cross-sectional view of the flexible interconnectassembly in FIG. 14A shows additional features of flexible interconnectassembly 190. Specifically, flexible interconnect assembly 190 comprisesconnector 1380 in addition to flexible interconnect circuit 100.Connector 1380 comprises housing 1381 and one or more conductiveelements 1382. Housing 1381 mechanically engages reinforcement metallayer 1370 of connector-support portion 1350. Each of one or moreconductive elements 1382 directly interfaces and is electrically coupledto a corresponding one of one or more conductive traces 150. One exampleof connector 1380 is a zero insertion force (ZIF) connector. Forexample, before the insertion of interconnect circuit 100 into connector1380, a lever or slider (provided in housing 1381) is moved into anunlocked position, pushing all the sprung conductive elements 1382 awayso that interconnect circuit 100 can be inserted with minimal force. Thelever or slider is then moved into a locked position, allowing theconductive elements 1382 to close and interface with conductive traces150 of interconnect circuit 100. In some examples, flexible interconnectcircuit 100 comprises notches 1340, each positioned on side edge 102 offlexible interconnect circuit 100 and extending at least throughreinforcement metal layer 1370 of connector-support portion 1350.Connector 1380 comprises retention pins 1385, such that each ofretention pins 1385 extends into a corresponding one of notches 1340.

FIGS. 15A-15D: Support Tabs for Attaching Flexible Interconnect Circuits

In some examples, flexible interconnect circuit 100 needs to be attachedto a support structure. For example, flexible interconnect circuit 100can be a car wire harness that is attached to various body panels duringits installation. Flexible interconnect circuit 100 can comprise supporttabs 1590 for this attachment as, e.g., is schematically shown in FIG.15A. The number and position of these support tabs 1590 depend on thelocation of the attachment points.

Referring to FIGS. 15B-15D, in some examples, flexible interconnectcircuit 100 comprises first insulator layer 151 and second insulatorlayer 152 stacked with first insulator layer 151 and forming primarycircuit portion 1501 and support tab 1590. Support tab 1590 extends fromthe edge of primary circuit portion 1501 as, e.g., shown in FIG. 15B. Insome examples, support tab 1590 is monolithic with primary circuitportion 1501. For example, first insulator layer 151 and secondinsulator layer 152 can be continuous sheets extending between supporttab 1590 and primary circuit portion 1501.

Referring to FIGS. 15B and 15C, support tab 1590 comprises support-tabopening 1592 for receiving fastener 1595 when securing flexibleinterconnect circuit 100 on support component 1599. Various examples offastener 1595 are within the scope such as a clip, a screw, a rivet, andthe like, e.g., as schematically shown in FIGS. 15C and 15D. Someexamples of support component 1599 are described above with reference toFIGS. 7B and 7C and can be also referred to as base structures.

Referring to FIGS. 15B-15D, in some examples, flexible interconnectcircuit 100 comprises conductive components (e.g., formed from the samemetal sheet), which in turn comprises conductive traces 150 and supportcomponent 1599. Conductive traces 150 are at least partially positionedbetween first insulator layer 151 and second insulator layer 152 inprimary circuit portion 1501. Support component 1599 is at leastpartially positioned between first insulator layer 151 and secondinsulator layer 152 in support tab 1590. Support component 1599 is usedto reinforce support tab 1590 providing additional strength.

In some examples, conductive traces 150 and support component 1599 areformed from the same materials (e.g., copper, aluminum) and/or have thesame thickness (e.g., at least 100 micrometers). For example, conductivetraces 150 and support component 1599 can be formed by patterning thesame metal sheet.

In some examples, support component 1599 is electrically isolated fromeach of conductive traces 150, e.g., as shown in FIG. 15B. For example,conductive traces 150 can be used for carrying power and/or signalbetween different parts of flexible interconnect circuit 100. At thesame time, support component 1599 may come in electrical contact withfastener 1595 and/or support component 1599. Alternatively, supportcomponent 1599 is monolithic with at least one of conductive traces 150,e.g., operable as a ground wire (not shown).

Referring to FIG. 15B, in some examples, conductive traces 150 extend ina first direction, at least proximate to support tab 1590. Support tab1590 extends from the edge of primary circuit portion 1501 in a seconddirection, substantially perpendicular to the first direction.

Referring to FIG. 15D, in some examples, second insulator layer 152comprises second-insulator opening 1594 that is larger and concentricwith support-tab opening 1592. Second insulator layer 152 partiallyexposes the surface of support component 1599 and allows fastener 1595to interface the surface of support component 1599. For example, thisdirect interface may be used to form an electric connection, e.g., whensupport component 1599 and fastener 1595 are used for groundingpurposes.

FIGS. 16A-16G: Attaching Connectors to Circuits with Traces HavingTemporary Support Links

In some examples, conductive traces 150 extend past the edges of firstinsulator layer 151 and second insulator layer 152 and can be used toform electrical connections, e.g., to connector conductive traces. Ifsuch conductive traces 150 are left unsupported (e.g., before formingthese electrical connections), these conductive traces 150 can changetheir orientations (e.g., bend) and even contact each other (e.g.,potentially causing electrical shorts). To avoid such issues, when suchconductive traces 150 are formed, flexible interconnect circuit 100 caninclude support end 155 to which the ends of conductive traces 150extend and connect to, e.g., as schematically shown in FIG. 16A.Specifically, support end 155 is a temporary part of flexibleinterconnect circuit 100 that is later removed, e.g., when a connectoris attached to flexible interconnect circuit 100, e.g., as schematicallyshown in FIGS. 16E-16G and described below. Returning to FIG. 16A, eachconductive trace 150 is connected to support end 155 by temporarysupport link 154, which can be monolithic with conductive trace 150. Forexample, all conductive traces 150 (forming the same conductive layer)and all temporary support links 154 (supporting these conductive traces150) can be formed from the same metal sheet (e.g., foil) by patterningthis sheet using various techniques. However, unlike conductive traces150, the corresponding temporary support links 154 have a much weakermechanical structure resulting in the fracturing of these temporarysupport links 154 when the force is applied to these temporary supportlinks 154 and/or to conductive traces 150. For example, the tensilestrength of these temporary support links 154 can be less than 50% thanthat of conductive traces 150 or less than 25% or even less than 10%.This difference in the tensile strength causes the fracture of temporarysupport links 154 before the fracture of any conductive traces 150.

Different examples of achieving this weaker mechanical structure areshown in FIGS. 16B-16D. Specifically, FIG. 16B illustrates temporarysupport link 154 having a smaller thickness than that of conductivetrace 150. In some examples, the thickness of temporary support link 154can be less than 50% than that of conductive trace 150 or less than 25%or even less than 10%. Various techniques (e.g., such as etching,ablation, and the like) can be used to achieve this thickness difference(i.e., forming temporary support link 154 from a portion of conductivetrace 150). FIG. 16C illustrates another example in which temporarysupport link 154 has a smaller width than that of conductive trace 150.In some examples, the width of temporary support link 154 can be lessthan 50% than that of conductive trace 150 or less than 25% or even lessthan 10%. Various patterning techniques can be used to achieve thiswidth difference (i.e., forming temporary support link 154 from aportion of conductive trace 150). FIG. 16D illustrates yet anotherexample in which temporary support link 154 has cuts/perforations 156,which reduce the integrity of temporary support link 154. Variouscutting/patterning techniques can be used to form thesecuts/perforations in a portion of conductive trace 150 thereby formingtemporary support link 154.

Referring to FIG. 16A, conductive traces 150 extending past the edges offirst insulator layer 151 and second insulator layer 152 to temporarysupport links 154 can be referred to as contact portions 153. At thisstage, these contact portions 153 are connected and monolithic withtemporary support links 154, which support these contact portions 153relative to supporting end 155. Specifically, additional parts ofconductive traces 150 can extend into supporting end 155 and besupported relative to each other by first insulator layer 151 and secondinsulator layer 152. Supporting end 155, temporary support links 154,contact portions 153, and remaining parts of flexible interconnectcircuit 100 can be formed by patterning three sheets (e.g., firstinsulator layer 151, second insulator layer 152, and metal foil formingall conductive components, including conductive traces 150 extendingbetween first insulator layer 151 and second insulator layer 152).

FIGS. 16E-16G are schematic views of different stages while attachingconnector 1610 to flexible interconnect circuit 100 of FIGS. 16A-16B, inaccordance with some examples. In these examples, connector 1610 isformed by first connector portion 1611 and second connector portion1612. First connector portion 1611 can include connector conductivetraces 1613 that are designed to connect to contact portions 153 offlexible interconnect circuit 100. Referring to FIG. 16E, firstconnector portion 1611 is positioned within alignment cavity 1602 ofassembly fixture 1600. Assembly fixture 1600 can also include alignmentpins 1604, which can extend through corresponding aligning features offlexible interconnect circuit 100 thereby providing the X-Y alignment offlexible interconnect circuit 100 to first connector portion 1611.

Referring to FIG. 16E, at this stage, contact portions 153 of flexibleinterconnect circuit 100 extend over connector conductive traces 1613and are supported by temporary support links 154. As noted above,temporary support links 154 help to maintain the alignment of contactportions 153, e.g., within the X-Y plane and now relative to connectorconductive traces 1613. Referring to FIG. 16F, as second connectorportion 1612 advances to flexible interconnect circuit 100 andeventually engages first connector portion 1611, second connectorportion 1612 pushes on contact portions 153 and/or temporary supportlinks 154 and eventually fractures temporary support links 154 therebyfreeing the ends of contact portions 153 from support end 155 andallowing contact portions 153 to move toward and engage/interface/formelectrical connections with connector conductive traces 1613. In someexamples, second connector portion 1612 may also engage/be attached tofirst connector portion 1611 thereby forming a connector body. FIG. 16Gillustrates an assembly comprising flexible interconnect circuit 100 andconnector 1690 attached to flexible interconnect circuit 100 during thestages shown above in FIGS. 16E-16G.

FIGS. 17A-17C: Examples of Laser Welding Conductive Layers ThroughInsulator Layer

Conductive traces 150 of the same or multiple flexible interconnectcircuits 110 often need to be electrically interconnected. At the sametime, these conductive traces 150 are typically positioned between firstinsulator layer 151 and second insulator layer 152. If conductive traces150 are exposed while forming various electrical connections (e.g., bypartially removing first insulator layer 151 and second insulator layer152 from the connection area), additional insulators are often needed toseal conductive traces 150, which adds processing steps and components.

Some methods of connecting conductive traces 150, such as resistancewelding and ultrasonic welding, require direct contact with thesecomponents. Laser welding does not require any direct physical contactbut requires a laser beam to reach the surface of one conductive trace150 to heat and partially melt this conductive trace 150 as well asanother component positioned underneath to form a weld nugget. While adirect line of sight can be used between a laser welder and a topconductive component, the direct line of sight is not required. However,any components positioned between the laser welder and the topconductive component should be penetrable to the laser beam.

FIG. 17A is a schematic side cross-sectional view of flexibleinterconnect circuit 100 with first conductive layer 1701 and secondconductive layer 1702 being laser welded through first insulator layer151 positioned on the path of laser beam 1709, in accordance with someexamples. During this laser welding, laser beam 1709 passes throughfirst insulator layer 151 and interacts with first conductive layer 1701causing first conductive layer 1701 to partially melt and form weldnugget 1703 together with second conductive layer 1702. FIG. 17B is aschematic top view of flexible interconnect circuit 100 illustratingweld nugget 1703 formed in first conductive layer 1701 and secondconductive layer 1702 and positioned under first insulator layer 151.

FIG. 17C is a process flowchart corresponding to method 1790 for laserwelding first conductive layer 1701 and second conductive layer 1702 offlexible interconnect circuit 100 through first insulator layer 151positioned on the path of laser beam 1709, in accordance with someexamples. In some examples, method 1790 comprises directing (block 1792)laser beam 1709 from laser welder 1708 to flexible interconnect circuit100 such that laser beam 1709 passes through first insulator layer 151of flexible interconnect circuit 100 and heats first conductive layer1701 positioned under first insulator layer 151 and also heats secondconductive layer 1702 positioned under first conductive layer 1701. Thisheating forms weld nugget 1703 between first conductive layer 1701 andsecond conductive layer 1702, wherein first insulator layer 151 istransparent to first insulator layer 151.

In some examples, first conductive layer 1701 and second conductivelayer 1702 comprise one or more materials selected from the groupconsisting of copper and aluminum.

In some examples, flexible interconnect circuit 100 further comprisessecond insulator layer 152 such that first conductive layer 1701 andsecond conductive layer 1702 are stacked and sealed between firstinsulator layer 151 and second insulator layer 152 when directing laserbeam 1709 from laser welder 1708 to flexible interconnect circuit 100as, e.g., is schematically shown in FIG. 17A.

In some examples, first insulator layer 151 is at least partially meltedor removed from the above weld nugget 1703. Alternatively, firstinsulator layer 151 seals weld nugget 1703 from the environment afterweld nugget 1703 is formed.

Flexible interconnect circuit 100 fabricated in accordance with method1790 can be used for various applications such as car seats, passengercabin applications for low-voltage wiring, and the like. In theseapplications, exposed conductors are not desired. For example, method1790 can comprise (block 1792) directing laser beam 1709 from laserwelder 1708 to flexible interconnect circuit 100.

FIGS. 18A-18C: Flexible Interconnect Circuits

FIG. 18A is a schematic planar view of flexible interconnect circuitassembly 190 in a pre-folded state, similar to the one described abovewith reference to FIG. 1A. FIG. 18B is a schematic cross-sectional viewof flexible interconnect circuit assembly 190 in FIG. 18A. In additionto various features of flexible interconnect circuit assembly 190described above with reference to FIGS. 1A-4B, flexible interconnectcircuit assembly 190 (shown in FIGS. 18A and 18B) comprises molded seals201, positioned on various portions of flexible interconnect circuit100. In various examples, molded seal 201 may be overmolded onto therespective portions of flexible interconnect circuit 100, such as firstinsulating layer 151 and second insulating layer 152. Molded seals 201provide the protection, sealing, and support for passing flexibleinterconnect circuit 100 through openings or gaps in a structure or forpassing flexible interconnect circuit 100 into various components orassemblies (e.g., a control circuit box). In various examples, supportfeatures for the overmolded portions of the flex circuit may also bedescribed herein.

Molded seal 201 may be formed (e.g., molded) from rubber, plastic,composites, and/or other material appropriate for overmolding. Variousexamples of such materials may include, for example, butyl (e.g.,isobutylene isoprene elastomer), nitrile, styrene-butadiene rubber(SBR), polyvinyl chloride (PVC), vulcanized rubber, ethylene propylenediene monomer rubber (EPDM) rubber, and/or other such materials. Thematerial(s) used may vary based on application. For applications thatrequire resistance to water, steam, alkalis, and/or other conditions,butyl may be used. Nitrile and/or SBR may provide damping and good hottear strength as well as resistance to certain oils, alcohol, and othermaterials. PVC grommets, vulcanized rubber, or EPDM may also be used(e.g., for non-injection molding overmolding manufacturing techniques,such as compression molding or transfer molding).

Molded seal 201 may allow for flexible interconnect circuit assembly 190to pass through various features that may not provide sufficient supportto flexible interconnect circuit 100 and/or may damage flexibleinterconnect circuit 100. Molded seal 201 may, thus, provide protectionand/or support to portions of flexible interconnect circuit 100,allowing for flexible interconnect circuit assembly 190 to pass through,undamaged, various openings and/or regions (e.g., opening). Molded seal201 may, additionally or alternatively, provide sealing for openingsthat allow for flexible interconnect circuit 100 to pass through. Thus,for example, electronic control unit (ECU) boxes may need to be sealedfrom the environment (e.g., sealed to prevent moisture, dust, or otherforeign objects from entering the ECU box). As the opening that allowsfor flexible interconnect circuit 100 to pass through on the ECU box maynot conform perfectly to flexible interconnect circuit 100, molded seal201 may provide a compressible seal that can fill the opening andprevent ingress of foreign objects into the ECU box. In various otherexample examples, molded seals may be utilized to provide sealing asdoor seals, liftgate or tailgate seals, seals within the interior of avehicle, seals within the engine bay of a vehicle, and/or for variousother applications that may require sealing.

Molded seal 201 may be formed through various techniques. Suchtechniques may include, for example, overmolding and insert molding. Themolding techniques may include, for example, injection molding,compression molding, transfer molding, and/or other single-shot ormulti-shot molding processes. In some examples, molded seal 201 may bemolded with a process (e.g., injection) temperature that is lower thanthe melting point of flexible interconnect circuit 100 or, morespecifically, lower than the melting point of various components (e.g.,first insulating layer 151, second insulating layer 152, and variousother adhesives and insulators used for insulating and sealingconductive traces 150). However, in examples where overmoldingtemperatures exceeds the acceptable temperatures of these components(e.g., injection temperature for certain types of thermoplastics may bebetween 180-240° C.), protector collar 210 may be utilized to preventdamage to flexible interconnect circuit 100 (e.g., by providing athermal barrier thereby preventing melting and/or damage from moldingpressures) and/or hold flexible interconnect circuit 100 in the correctposition during molding. Protector collar 210 may, in certain examples,be a nylon, composite, steel, aluminum, or other like materials. Whenconductive materials are used, such base materials may be accordinglyinsulated. Protector collar 210 may, thus, be positioned around thecorresponding section of flexible interconnect circuit 100 before moldedseal 201 is molded around flexible interconnect circuit 100.

FIGS. 19A-19E: Examples of Flexible Interconnect Circuits with Carriers

FIGS. 19A, 19B, 19C, 19D, and 19E, illustrate different views offlexible interconnect circuit assembly 190 comprising flexibleinterconnect circuit 100, molded seal 201, and circuit carrier 330.Specifically, flexible interconnect circuit 100 may be positioned withincircuit carrier 330. FIG. 19B is a vertical view of assembly 190 andFIG. 19A illustrates a cross-section view of flexible interconnectcircuit assembly 190 along line 19A-19A of FIG. 19B.

Circuit carrier 330 may be an example of a structure that providessupport for a flexible interconnect circuit 100. For example, circuitcarrier 330 may support a flexible interconnect circuit 100 acrossopenings. In various examples, carrier 330 is a rigid or semi-rigidstructure that provides support to flexible interconnect circuit 100where needed (e.g., over a gap, such as over the opening span). In someexamples, carrier 330 also allows some bending rigidity to allowsupported movement and protection to flexible interconnect circuit 100.

In various examples, flexible interconnect circuit 100 is positionedonto circuit carrier 330 and may be secured to circuit carrier 330 by,for example, an adhesive, such as a pressure-sensitive adhesive (PSA).In various examples, other fastening techniques, such as mechanicalfasteners and other techniques, may be employed, additionally oralternatively, to secure flexible interconnect circuit 100 onto circuitcarrier 330.

In various examples, circuit carrier 330 may include cover 320 and basestructure 312. Flexible interconnect circuit 100 may be positionedbetween cover 320 and base structure 312. Cover 320 may be coupled tobase structure 312 (e.g., according to techniques described herein), tohold flexible interconnect circuit 100 within circuit carrier 330.

In various examples, molded seal 201 may be positioned around flexibleinterconnect circuit 100. Molded seal 201 is positioned between flexibleinterconnect circuit 100 and circuit carrier 330 and provides forprotection for flexible interconnect circuit 100 and/or sealing of theopening within circuit carrier 330 that flexible interconnect circuit100 passes within. Molded seal 201 may be any type of molded seal asdescribed herein.

FIGS. 19C-E illustrate a technique of coupling a flexible interconnectcircuit to a circuit carrier. In FIG. 19C, flexible interconnect circuit100, which may be overmolded with molded seal 201, is inserted intobottom portion 332. Bottom portion 332 may include cavity 338 forreceiving flexible interconnect circuit 100. Cavity 338 may be defined,at least in part, by sides 334 and 336, which are configured to holdflexible interconnect circuit 100 within cavity 338.

In FIG. 19D, after flexible interconnect circuit 100 has been insertedinto cavity 338, cover portion 340 may be placed over cavity 338. Coverportion 340 may hold flexible interconnect circuit 100 in place withincavity 338. In some examples, base portion 332 and cover portion 340 areseparate individual pieces (e.g., separately attached to base structure312 and cover 320, respectively, or may be a all or a portion thereof ofbase structure 312 and cover 320, respectively).

In such examples, cover portion 340 may rotate into position along hinge342. In additional examples, base portion 332 and cover portion 340 maybe a single continuous assembly. In such examples, cover portion 340 maybe hinged to base portion 332 via hinge 342.

In FIG. 19E, cover portion 340 may be moved into a closed position. Theclosed position may hold flexible interconnect circuit 100 within cavity338. In certain examples, molded seal 201 may be compressed when coverportion 340 is in the closed position, to provide protection and sealingto flexible interconnect circuit 100.

Cover portion 340 may include securing mechanism 344. Securing mechanism344 may be, for example, a latch or catch which will attach onto anotherportion of the carrier (e.g., base portion 332) in order to secure coverportion 340 in a closed position. For example, securing mechanism 344may include a hook or snap that may interface with an insertion point onthe external side of bottom portion 332. An alternate configuration forsecuring mechanism 344 is shown by securing mechanism 344-A, which mayalso have a hooked configuration. Securing mechanism 344-A may beinserted into a recess positioned at the top side of bottom portion 332.

FIGS. 20A and 20B illustrate cross-sectional views of additionalexamples of flexible interconnect circuit assembly 190. Flexibleinterconnect circuit assembly 190 includes space 410 between flexibleinterconnect circuit 100 and cover portion 402 as well as base portion401. In the examples shown in FIG. 20 , flexible interconnect circuitassembly 190 does not include a molded seal. FIG. 20B illustratesanother example with flexible interconnect circuit assembly 190comprising molded seal 201, positioned within space 410. Molded seal 201thus acts as a gasket for flexible interconnect circuit 100, providingfor sealing as well as preventing unrestrained movement of flexibleinterconnect circuit 100 within space 410 and, thus preventing damagefrom such unrestrained movement.

FIGS. 21A-G: Forming of Flexible Interconnect Circuits

Various examples of forming molded seal flexible interconnect circuitsare described herein. For the purposes of this disclosure, it isappreciated that various examples may utilize one, some, or all suchfeatures described. Thus, for example, molded seal flexible interconnectcircuits that are formed with lower pressure molding techniques (e.g.,lower pressures than injection molding, such as compression molding ortransfer molding) may not include one, some, or all such featuresdescribed (e.g., a protector collar may not be used for such formingtechniques).

FIGS. 21A and 21B illustrate schematic planar views illustrating atechnique of forming a molded seal flexible interconnect circuit, inaccordance with some examples. FIG. 21A illustrates forming scenario 700for molding seals onto flexible interconnect circuit 100. In formingscenario 700, edges 702 and 704 are the edges of the cavity for formingmolded seals on flexible interconnect circuit 100. Flexible interconnectcircuit 100 further includes one or more support tabs 690 with openings692. Support tabs 690 of forming scenario 700 may be positioned withinedges 702 and 704 of the tooling and, thus, positioned within themolding cavity of the tool during molding.

FIG. 21B illustrates forming scenario 710 where a portion of flexibleinterconnect circuit 100 is positioned within molding cavity 712. Themolding tool of molding cavity 712 may include pins configured to passthrough openings 692. Such pins may hold flexible interconnect circuit100 in place during molding, preventing the deformation of flexibleinterconnect circuit 100 from the pressures of molding. Molding cavity712 may also include indent 714. Indent 714 may form a depression withinthe molded seal, allowing for the molded seal and, thus, flexibleinterconnect circuit 100, to be secured within an opening.

FIGS. 21C and 21D illustrate schematic planar views illustrating anothertechnique of forming a molded seal flexible interconnect circuit, inaccordance with some examples. FIG. 21C illustrates forming scenario 800that includes flexible interconnect circuit 100 which includes aplurality of support tabs 690 with openings 692 that are positionedoutside of the area defined by edges 802 and 804. Thus, the plurality ofsupport tabs 690 is positioned proximate to the molded seal. Edges 802and 804 are the edges of the tooling for forming molded seals onflexible interconnect circuit 100. Thus, support tabs 690 are positionedoutside of the molding cavity.

FIG. 21D illustrates forming scenario 810 where a portion of flexibleinterconnect circuit 100 is positioned within molding cavity 812. Themolding tool associated with molding cavity 812 may include pinsconfigured to pass through openings 692. Molding cavity 812 may alsoinclude indent 814 for forming a depression within the molded seal.

FIGS. 21E, 21F, and 21G illustrate schematic planar views illustrating afurther technique of forming a molded seal flexible interconnectcircuit, in accordance with some examples. FIG. 9A illustrates formingscenario 900 that includes flexible interconnect circuit 100 thatincludes support tabs 690 with openings 692. Flexible interconnectcircuit 100 may be configured to be positioned within a molding cavitydefined by edges 902 and 904.

In forming scenario 910 of FIG. 21F, protector collar 912 is insertedaround flexible interconnect circuit 100. Protector collar 912 mayprovide protection to flexible interconnect circuit 100 from thepressure, temperature, or other aspects of molding. Protector collar 912may be as described herein.

In forming scenario 920 of FIG. 21G, molding cavity 914 is positionedover flexible interconnect circuit 100 and protector collar 912. Themolding tool of molding cavity 914 may, thus, form a molded seal overprotector collar 912. In various examples, protector collar 912 may bepositioned over flexible interconnect circuit 100 and may remainpositioned over flexible interconnect circuit 100 after forming of themolded seal. Pins may be positioned through openings 692 to holdflexible interconnect circuit 100 in place during forming of the moldedseal. Molding cavity 914 may also include indent 916 for forming adepression within the molded seal.

FIG. 22 illustrates a process flow chart corresponding to an examplemethod for forming a molded seal flexible interconnect circuit, inaccordance with one or more examples. FIG. 22 illustrates process 1000for forming a molded seal flexible interconnect circuit and assemblingthe molded seal flexible interconnect circuit. In 1002, the flexibleinterconnect circuit is formed. Thus, for example, the various layersand electrical circuits and/or traces of the flexible interconnectcircuit is formed in 1002.

In optional 1004, a protector collar is applied to one or more portionsof the flexible interconnect circuit. The protector collar may be asdescribed herein and may protect the flexible interconnect circuit fromthe pressure and/or temperatures of molding. Certain forming techniquesmay not require a protector collar and, thus, no protector collar may bepositioned on flexible interconnect circuit 100 in such techniques.

In optional 1006, flexible interconnect circuit 100 may be assembled.Thus, any additional components, such as a connectors may be assembledin 1006. Additionally or alternatively, the flexible interconnectcircuit may be cut and/or bent as required.

In 1008, one or more seals may be overmolded onto the flexibleinterconnect circuit, according to the techniques described herein. Invarious examples, the flexible interconnect circuit may be supported(e.g., via pins inserted into openings of the flexible interconnectcircuit) and/or protected (e.g., by protector collars) as describedherein. Various other techniques may utilize molding of parameters(e.g., of certain pressures and/or temperatures) that do not requirereinforcement or support of a flexible interconnect circuit duringmolding. In 1010, the finished flexible interconnect circuit is producedand is assembled (e.g., assembled to a vehicle).

Alternatively, the seal can be overmolded before assembly and otheroperations for finalizing the flexible interconnect circuit in optional1008.

FIGS. 23A-23C: Example Assemblies

FIGS. 23A-C illustrate schematic planar views illustrating molded sealflexible interconnect circuits in various assemblies, in accordance withsome examples. As illustrated in FIGS. 23A-C, flexible interconnectcircuits with molded seal may allow for sealing and protection whenpassing through various openings. Such sealing may be an inherentprotection of flexible interconnect circuits with molded seals and,thus, an additional seal or other components may not be needed toprovide for the required sealing and/or protection. Accordingly, partcounts, attendant logistics, and assembly time may be reduced.

FIG. 23A illustrates assembly 2300 that includes control unit 2302 andflexible interconnect circuit 100. Flexible interconnect circuit 100includes molded seal 201 and electrical connection 233. Control unit2302 may be, for example, an electronic control unit (ECU). Flexibleinterconnect circuit 100 may terminate inside of control unit 2302.Thus, for example, electrical connection 233 may be a connector and/oran electrical connection that is coupled to various circuitry withincontrol unit 2302 (e.g., a soldered connection).

Flexible interconnect circuit 100 may pass into control unit 2302through opening 2304 of control unit 2302. Molded seal 201 may bepositioned on flexible interconnect circuit 100 at a location that wouldallow molded seal 201 to provide protection and/or sealing whereflexible interconnect circuit 100 passes through opening 2304. Thus, forexample, control unit 2302 may require certain sealing characteristics(e.g., to prevent dust intrusion). As opening 2304 does not perfectlyconform with flexible interconnect circuit 100, molded seal 201 may sealopening 2304.

FIG. 23B illustrates assembly 2310 that includes bulkhead 2312 andflexible interconnect circuit 100. In various examples, bulkhead 2312may be a partition, firewall, and/or another such structure. Aselectrical connections may need to pass from one side of bulkhead 2312to the other side, bulkhead 2312 may include opening 2314 that allowsfor flexible interconnect circuit 100 to pass from one side to the otherside (e.g., from one side of a vehicle to another side of the vehicle).

Flexible interconnect circuit 100 includes molded seal 201. As opening2314 may be formed from, for example, sheet metal or machined metal andmay, thus, include sharp edges that may damage an electrical circuit,molded seal 201 may provide protection to the portion of flexibleinterconnect circuit 100 that passes through opening 2314. Molded seal201 may also provide sealing for opening 2314 and, thus, seal off oneside of bulkhead 2312 from the other side.

FIG. 23C illustrates assembly 2320 that includes component 2390 andflexible interconnect circuit 100. Component 2390 includes opening 2394.Component 2390 may be, for example, a door, fascia, window, firewall,and/or another such component. Component 2390 may include sealingrequirements. As shown in FIG. 23C, molded seal 201 of flexibleinterconnect circuit 100 may be compressible and may expand to occupythe area of opening 2394, allowing for sealing of opening 2394 thatflexible interconnect circuit 100 passes through. Accordingly, moldedseal 201 may provide protection from the outside environment of avehicle even though portions of flexible interconnect circuit 100 maypass from a “dry” interior side of the vehicle (where liquid and dustintrusion would need to be eliminated or minimized) to a “wet” exteriorside of the vehicle.

CONCLUSION

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedexamples (and/or aspects thereof) may be used in combination with eachother. In addition, many modifications may be made to adapt a particularsituation or material to the teachings presented herein. Dimensions,types of materials, orientations of the various components, and thenumber and positions of the various components described herein areintended to define parameters of some examples and are by no meanslimiting and are merely examples. Many examples and modifications withinthe spirit and scope of the claims will be apparent to those of skill inthe art upon reviewing the above description.

1. A method of forming a flexible interconnect circuit assembly, themethod comprising: providing a flexible interconnect circuit comprisinga first circuit portion and a second circuit portion monolithicallyintegrated with the first circuit portion, wherein: each of the firstcircuit portion and the second circuit portion is an elongated structureextending parallel to a primary axis of the flexible interconnectcircuit, each of the first circuit portion and the second circuitportion comprises a first side and a second side opposite to the firstside, and the first side of the first circuit portion and the first sideof the second circuit portion face in a same direction; folding thesecond circuit portion relative to the first circuit portion such thatthe second circuit portion is no longer parallel to the primary axis ofthe flexible interconnect circuit and such that the second side of thefirst circuit portion and the second side of the second circuit portionface in opposite directions after folding; attaching a bonding film tothe second side of the first circuit portion and the first side of thesecond circuit portion; and attaching a temporary support film to thebonding film such that the first side of the first circuit portion andthe second side of the second circuit portion face the temporary supportfilm.
 2. The method of claim 1, wherein: the first circuit portionterminates with a first connector, and the first connector and a part ofthe first circuit portion, adjacent to the first connector, extendoutside a boundary of the bonding film.
 3. The method of claim 2,wherein the first connector and the part of the first circuit portion,adjacent to the first connector, overlap with a boundary of thetemporary support film.
 4. The method of claim 1, wherein, beforefolding, the first circuit portion and the second circuit portion arecoplanar.
 5. The method of claim 1, wherein, after folding, a part ofthe first side of the first circuit portion directly interfaces with apart of the first side of the second circuit portion.
 6. The method ofclaim 1, wherein: the first side of the first circuit portion and thefirst side of the second circuit portion is formed by a first insulatinglayer, which is monolithic, and the second side of the first circuitportion and the second side of the second circuit portion is formed by asecond insulating layer, which is monolithic and bonded to the firstinsulating layer.
 7. The method of claim 6, wherein each of the firstcircuit portion and the second circuit portion comprises one or moreconductive traces, positioned between the first insulating layer and thesecond insulating layer such that the first insulating layer and thesecond insulating layer are bonded together around the one or moreconductive traces.
 8. The method of claim 7, wherein providing theflexible interconnect circuit comprises forming the one or moreconductive traces of the first circuit portion and the second circuitportion by patterning a metal foil.
 9. The method of claim 6, wherein:the first circuit portion and the second circuit portion form a primarycircuit portion, the flexible interconnect circuit comprises supporttabs, each formed by at least the first insulating layer and the secondinsulating layer and extending from an edge of the primary circuitportion and monolithic with the primary circuit portion, and each of thesupport tabs comprises a support-tab opening for receiving a fastenerwhen securing the flexible interconnect circuit.
 10. The method of claim9, wherein: the flexible interconnect circuit comprises conductivetraces and a support component, which are formed from same conductivematerials and have same thicknesses, the conductive traces are at leastpartially positioned between the first insulating layer and the secondinsulating layer in the primary circuit portion, and the supportcomponent is at least partially positioned between the first insulatinglayer and the second insulating layer in the support tabs and is used toreinforce the support tabs providing additional strength.
 11. The methodof claim 10, wherein the support component is electrically isolated fromeach of the conductive traces.
 12. The method of claim 10, wherein thesupport component is monolithic with at least one of the conductivetraces.
 13. The method of claim 10, wherein: the second insulating layercomprises a second-insulator opening that is larger and concentric withthe support-tab opening, and the second insulating layer at leastpartially exposes the support component.
 14. The method of claim 1,wherein the first circuit portion and the second circuit portion,extending parallel to each other, are separated by a slit.
 15. Themethod of claim 1, further comprising arranging the flexibleinterconnect circuit into a shipping configuration selected from thegroup consisting of a planar sheet and a roll, wherein the rollcomprises additional flexible interconnect circuits.
 16. A flexibleinterconnect circuit assembly comprising: a flexible interconnectcircuit comprising a first circuit portion and a second circuit portionmonolithically integrated with the first circuit portion, wherein: eachof the first circuit portion and the second circuit portion comprises afirst side and a second side opposite the first side, the first side ofthe first circuit portion and the first side of the second circuitportion is formed by a first insulating layer, the second side of thefirst circuit portion and the second side of the second circuit portionis formed by a second insulating layer, bonded to the first insulatinglayer, and the second circuit portion is folded relative to the firstcircuit portion such that the second circuit portion is not parallel tothe first circuit portion and such that the first side of the firstcircuit portion and the first side of the second circuit portion face inopposite directions; a bonding film attached to the second side of thefirst circuit portion and the first side of the second circuit portion;and a temporary support film attached to the bonding film such that thefirst side of the first circuit portion and the second side of thesecond circuit portion faces the temporary support film.
 17. Theflexible interconnect circuit assembly of claim 16, wherein: the firstcircuit portion terminates with a first connector, and the firstconnector and a part of the first circuit portion, adjacent to the firstconnector, extend outside a boundary of the bonding film.
 18. Theflexible interconnect circuit assembly of claim 17, wherein the firstconnector and the portion of the first circuit portion, adjacent to thefirst connector, overlap with a boundary of the temporary support film.19. The flexible interconnect circuit assembly of claim 16, wherein: thefirst insulating layer is monolithic, and the second insulating layer ismonolithic.
 20. The flexible interconnect circuit assembly of claim 16,wherein each of the first circuit portion and the second circuit portioncomprises one or more conductive traces, positioned between the firstinsulating layer and the second insulating layer such that the firstinsulating layer and the second insulating layer are bonded togetheraround the one or more conductive traces.